Conversation Between Jonathan H and DanoM

The illumination wire should get 12V when the car's headlights are on and 0V when the headlights are off; this tells the head unit to go into night mode and dim the screen. I would think that information gets to the head unit via the CANBUS but I will have to check the wiring diagram and/or check with a multimeter. Whether or not this information is relayed via CANBUS may also depend on whether or not you have automatic headlights. Are you using a CANBUS decoder? Do you have automatic lights? You are mentioning button color but I am not sure which button you are referring to. Do you mean the screen background color?

Jonathan, sorry if this is the wrong way to reach out. I reviewed your post on the Cayenne Android installation and I wanted to ask a wiring question if I could. I just did this myself over the weekend, my unit is the one for Cayenne's with the knobs (maybe you've seen it when you were shopping) but operates the same way as yours. The one thing I can't seem to get working is the button color. You're supposed to be able to change that and mine stays white (although I can vary the brightness level). There was an Illumination wire from the HU harness that I wasn't sure where to connect to as the stock PCM didn't use that (I believe it gets the signal elsewhere). I tried not connecting it and also tied it to 12v+ with no luck. Dealing with the "Tech Support" from China has proven useless. I'd like to figure out how to fix this issue if I can and hoping its a wiring issue or setting or I've missed somewhere as I don't want to have to deal with returning this unit, etc.